The present invention relates to a friction clamping apparatus.
As a conventional friction clamping apparatus, known is that shown in FIG. 4, in which a sleeve 01 having a collar portion 02 is fittingly inserted through an outer cylinder 03 so that the collar portion 02 is engaged with one end surface of the outer cylinder 03 to thereby form a restraint pressure chamber between the outer cylinder 03 and the outer circumferential surface of a small diameter portion of the sleeve 01, and a shaft 07 is slidably fittingly inserted through the hole of the sleeve 01. A pressurized fluid is supplied into the restraint pressure chamber through a leading hole 05 so as to reduce the diameter of the sleeve 01 to urge the sleeve 01 against the outer circumferential surface of the shaft 07 to thereby produce a friction force between the sleeve 01 and the shaft 07 to restrain the shaft.
In such a conventional apparatus, the sleeve receives a reaction force against a force F, given to the shaft at the time of restraint concentrically in the vicinity of the collar portion of the sleeve, so that it is necessary to make the sleeve thick enough to have strength against the reaction force. As a result, not only has there been a problem that the apparatus becomes large in size, but, in the worst case, there has been a problem that it is difficult to perform processing and assembling from the standpoint of accuracy in processing and assembling and also difficult to perform maintenance and inspection. There has been a further problem that the pressure for a pressurized fluid required for shrinking a sleeve becomes large.